Method and apparatus for conveying glass along loading equipment

ABSTRACT

An improvement is provided in methods for conveying a charge, or gob, of formable glass along glass loading equipment, from the point of severance of the gob to the point where the charge of formable glass is discharged into a mold for forming; the improvement essentially resides in increasing the effective glass contacting life of lubricants, which have been previously employed on the glass loading equipment, by providing a support coating for the previously employed lubricants, which support coating comprises a transition metal in a major amount applied from a flame spray or plasma spray and presents an abrasion-resistant, rough surface profile upon which the previously employed lubricants are then deposited.

THE INVENTION

The present invention is directed to the art of glass manufacturing and,more particularly, is directed to the art of conveying a charge offormable glass, or glass gob, from the point of its severance from amolten pool of glass to the point of its entry into a glass formingmold. More specifically, the present invention is directed toimprovements in methods for conveying a charge of formable glass uponloading equipment which carries a solid film glass lubricant layerthereon.

In the art of glass manufacturing molten glass is generally stored in aforehearth having a feeder, which feeder is provided at its bottom withan opening whereby the formable glass may discharge under the influenceof a reciprocating plunger. As the glass issues through this opening itis typically severed from the main body of the glass by appropriateshears. This charge of formable glass, or, as it is sometimes referredto, a glass gob, is then conveyed from its point of severance by theshears to an appropriate glass forming mold over, and along, what isgenerally referred to in the art as loading equipment. The conveying ofthe charge of molten glass over the loading equipment is typicallyaccomplished under the influence of gravity. The loading equipment, ingeneral, includes a member, which may be referred to as a deflector or ascoop, which serves to intercept the falling sheared gob and guide itinto a chute or trough member. In passing it should be mentioned thatoccasionally the deflector and the scoop are considered to be part ofthe chute or trough itself. This chute, or trough, presents in its crosssection an arcuate configuration which defines a track along which theglass charge is gravitationally conveyed in the direction of a suitableglass forming mold. The gob, or charge of formable glass, is then, inturn, guided into the mold by what is typically referred to in the artas a funnel or a deflector.

Important considerations are involved in conveying the gob or charge offormable glass from its point of severance to the mold. First, the timeof travel must be constant in order to insure efficient and uniformoperation. Second, the shape of the gob must not be significantlyaltered during the travel along the chute as such alteration may causedistortion in the finished article. Third, the surface of the glasscharge must not become chilled or contaminated; otherwise, the qualityof the finished article will not be suitable.

If chutes for conveying the glass are plain metal, and what is typicallyemployed for the loading equipment is either iron or aluminum, the hotgob or charge of formable glass has a tendency to become adhered to theloading equipment, resulting in either a failure to travel to the moldor a distortion in the shape of the gob. Either, or both of thesesituations are, obviously, unacceptable. As a result it has been commonpractice to lubricate the loading equipment by either intermittent orcontinuous application of oil, or oil base dopants. Such a treatment ofthe loading equipment facilitates the passage of the glass but it isonly temporary and necessitates frequent, or continuous, application ofthe oil or dopant. In spite of such continued application, the time oftravel of the gob or charge of formable glass is erratic. In addition,oil causes environmental pollution and has a tendency to form depositson the gob which remain in the finished article.

Because of the problems which exist in the foregoing type oflubrication, attempts have been made to solve this problem so as toprovide a method of conveying formable glass charges along the loadingequipment which method will provide a high quality product with minimumcontamination of the adjacent environment and which method is conductiveto a high production rate and low cost operation. Proposals have beenmade for providing an improved technique for conveying formable glasscharges along the loading equipment by providing the loading equipment,at least along a portion thereof which is in a glass contactinglocation, with a solid firm glass lubricant layer which typicallycomprises effective lubricating amounts of a lubricating pigmentdispersed in a polymeric binder. Such proposals are exemplified by U.S.Pat. No. 2,873,555, U.S. Pat. No. 2,758,421, and U.S. Pat. No. 3,479,206which patents are hereby incorporated by reference, especially withregard to their description of the loading equipment. In addition to theteachings of these patents proposals have been made that the loadingequipment be provided with a solid film lubricant layer of a suitablelubricating pigment, such as, for example graphite, dispersed in abinder system which is a cured, hard, thermoset organopolysiloxane andwhich organopolysiloxane can, optionally, include other materials suchas, for example, effective cure promoting amounts of a siloxane curepromoter, for example, melamine formaldehyde partial condensate resins.The latter term includes the lower akylated melamine formaldehydepartial condensate resins such as, for example, the C₁ -C₅ alkylatedmelamine formaldehyde partial condensate resins.

The proposals referred to immediately above have tended to minimize someof the problems but, nonetheless, are deficient with respect to theirglass-contacting, or effective, life. Thus, in themselves theseproposals do not solve the problem or satisfy the need in the art for alubricating technique, in conveying the charges of formable glass alongloading equipment, which technique is compatible with and conducive to ahigh speed, low cost operation for producing high quality wear withminimal, if any, undesirable pollution.

Thus, the object of this invention is to effectively increase the glasscontacting, lubricating life of the foregoing described solid film glasslubricant layers which have been employed on glass loading equipment soas to solve the problems and satisfy the needs in the art with respectto conveying formable glass charges along loading equipment.

In accordance with this invention, there is provided an improvement inprior art processes for forming glass articles comprising conveying acharge of formable glass over loading equipment to a forming mold andwherein at least a portion of the loading equipment carries, at alocation which is in contact with the conveyed glass charge (glasscontacting location), a solid film glass lubricant layer comprisingeffective lubricating amounts of a lubricating pigment dispersed in apolymeric binder; the improvement essentially resides in increasing theeffective lubricating life of the solid film glass lubricant layer bysupporting said solid film lubricant layer on the base metal of theloading equipment with a textured, or rough, support coating of a metal,i.e., the support coating of the metal is disposed intermediate thesolid film lubricant layer and the base metal of which the loadingequipment is fabricated.

In accordance with another feature of this invention, there is providedan improvement in prior art glass gob delivery chutes comprising afirst, or base, metal surface of the chute and a solid film glasslubricant layer carried by said base metal surface which lubricant layercomprises, for example, graphite dispersed in a cured, thermosetpolymer; the improvement resides in employing a supporting-metal layerfor the solid film lubricant which layer is disposed intermediate thefirst metal surface, i.e., the base metal surface of which the chute isfabricated, and said solid film lubricant layer. The supporting metallayer for the solid film lubricant is carried by a conventional deliverychute and has a rough surface to which the glass lubricant layer isattached. That is, the delivery chute instead of being a laminatedstructure of two layers, i.e., the metal of the chute, or deliveryequipment, and the solid film glass lubricant layer, will now be alaminate in which there is also provided intermediate the metal of thechute, or delivery equipment, and the solid film lubricant layer, asupporting layer of a metal for the solid film lubricant whichsupporting layer will have a roughened surface upon which the solid filmlubricant layer is carried and which layer is formed by flame sprayingor plasma spraying.

In accordance with another feature of this invention, there is providedan improvement in prior art methods for forming glass loading equipmentcomprising applying onto a glass contacting metal member, for example achute, a dispersion of a lubricating pigment, preferably graphite, in acurable thermosettable polymer and then curing the polymer to athermoset condition so as to bind the lubricating pigment therein andform a solid film, glass lubricant layer on the glass contacting metalmember; the improvement comprises increasing the effective lubricantlife of said layer by applying onto the surface of the metal member,prior to the application of the dispersion of the lubricating pigment inthe curable, thermosettable polymer, a transition metal in a high energyspray so as to form a metal layer on the member, e.g. a chute, whichlayer has a rough surface and serves as a support layer for thesubsequently applied solid film lubricant layer. The use of such glassloading equipment as provided herein for conveying severed glass to amold provides unexpectedly increased effective lubricating lives.

In Solid Lubricants by Campbell, Loser & Sneegas, NASA, Washington,D.C., May, 1966 at pages 7-17 bonded, solid lubricants are discussedand, more specifically, pretreatments such as, for example, vapor orgrit blasting, phosphating, sulfiding, anodizing etching, and the use ofdichromates and chemical films are disclosed. There is no recognition ordisclosure of the present invention concept, however, therein. Also inthis respect reference may be had to Survey of Solid Film Lubricants byD. B. McConnell, Wright Air Development Division, Proceedings of the AirForce-Navy-Industry Propulsion Systems Lubricants Conference, November1960, pages 113 to 127. In A Survey of Solid Lubricant Technology(Technical Report) by Peter Martin, Jr., Industrial Applications Report,Aerospace Research Application Center, U.S. Army Weapons Command, 1972at, for example, pages 9 and 16, plasma spraying is disclosed. There isno recognition, however, or teaching of the present invention therein.Processes involving flame spraying and processes involving flamespraying or plasma spraying, in order to obtain equipment used in glassmanufacture, are disclosed in U.S. Pat. No. 3,347,650 and in Britishpatent specification No. 1,333,055. There is, however, in neither ofthese references any recognition of the problem solved by applicants andthere is no teaching or suggestion, in either of these references, as tohow the present problem may be solved.

As previously indicated the art of conveying charges of formable glassfrom the point of severance, by shears, to the point of entry into anappropriate glass forming mold has been practiced by employing loadingequipment which may be considered to have been of a laminated two layerstructure. Essentially the present invention provides improvements inthe effective life of such loading equipment by providing, intermediatethe metal base of the loading equipment and the solid film lubricantlayer, a layer of a metal. This intermediate metal layer has a rough ortextured surface and serves as a support layer for the solid filmlubricant layer; the complementary action of the provided intermediatesupporting layer and the solid film lubricant layer, which is bondedthereto, enhances and provides superior and longer effective life forsuch glass loading equipment.

In order to obtain most desirable results the metal support layer willbe applied onto a cleaned surface of a conventional glass loadingequipment member, e.g., an aluminum or iron chute, and subsequent to theformation of the supporting metal layer thereon the solid film glasslubricant layer will be applied thereto using the techniques previouslyemployed for forming such layers. Most desirably the cleaning of theglass loading equipment will be done by baking that equipment, so as toburn off undesirable organic residuals, and then subsequently gritblasting the surface. The supporting metal layer is then applied ontothe metal portion of the glass loading equipment in a high energy spray.As used herein high energy spray means a flame spray or plasma sprayboth of which are conventional and are per se well known in the art. Themetal which is applied to form the support layer will be a hard metaland will, desirably, exhibit less glass wetting than the base metal ofthe glass loading equipment. The hardness of the support metal layer isnot critical and, in general, it may be stated that the harder the metalthe greater will be the realized increase in life of the deliveryequipment. Preferably the metal will have a melting point greater thanabout 1700° F.. Preferred metals are the transition metals i.e., thoseappearing to the right of the Group IIA elements and to the left of theGroup IIIA elements of the periodic chart; i.e., those metals appearingin Groups IIIB, IVB, VB, VIB, VIIB, VIIIB, IB and IIB, mixtures thereofand alloys thereof in which the alloy is at least about 50% by weight,and preferably at least about 60% by weight, of at least one of saidtransition metals. Especially preferred metals are nickel and chromiumwith a most desirable material being an alloy of about 60 to about 95%nickel and about 0.5 to 18% chromium; the balance being ingredients, oradjuvants, present as processing aids, for example fluxing agents, toenhance the known use of these materials in plasma or flame sprayapplications. Additionally, the metals which are applied by the highenergy spray, i.e., plasma spray or flame spraying will desirablyinclude transition metal carbides and/or transition metal nitrides insmall quantities which are sufficient to enhance the hardness. Typicallythe amounts of these carbides and/or nitrides when present will be onthe order of about 2% by weight to about 18% by weight. Thusparticularly preferred materials for the support metal layer willinclude about 60 to about 95% (wt.) nickel, about 0.5 to about 18%chromium, about 2-18% of at least one transition metal carbide ornitride and the balance being conventional processing aids. Thesematerials are well known and widely commercially available. Oneespecially suitable material is that supplied commercially by EutecticCastolin Institute, Flushing, N.Y. under their designation Diamax 19112and is a material of about 61% Ni and 7% Cr and about 12% by weight ofTungsten carbide; the balance by analysis shows the presence of aluminumand boron and also small amounts of calcium, magnesium, manganese iron,lead, silicon and titanium but the precise chemical species, i.e.,whether elemental or combined as for example an oxide was notdetermined. As indicated the flame spraying and plasma spray techniquesare per se well known in the art and such techniques will be routinelyemployed herein. Conventional flame sprayable and conventional plasmasprayable transition metals, as indicated above, will be employed in theflame spray or plasma spray application respectively. When using flamespray techniques it is generally preferred to apply the supporting metalcoating by means of commercially available oxyacetylene torches designedof flame spray fine particulate materials. Other flames such as, forexample, oxyhydrogen flames, can equally be employed. The techniquesutilized for plasma spray application are based on ionized gas plasmaand equipment for plasma spraying particulate materials may be procuredfrom numerous suppliers. In passing, it is generally preferred that theparticle size transition of the metal-containing material employed forforming the support layer be generally in the size range of about 1000microns to about 500 microns.

When metals of the type contemplated herein are sprayed onto a metalsurface by means of a flame spray or plasma spray i.e., the applicationof the metal in a high energy spray, the particles coalesce an formadherent layer on the base metal which inherently is defined by a roughor textured surface profile. This rough surface is employed as is, i.e.,no direct attempts are made to provide a smoother surface profile to thesupport metal such as, for example, as might be accomplished byapplication of additional heat to get better flow or such as, forexample, by machining the surface. This surface typically has aroughness on the order of about 500-600 microinches (arithmetic average)and may generally be considered as being a surface possessed ofmountains and valleys. The nature of this flame sprayed or plasmasprayed metal support layer with its hardness and surface profile ofmountains and valleys complements and apparently interacts with thesolid film lubricant layer to provide highly improved effectiveoperating life for glass loading equipment.

In passing, it should be mentioned that in some instances it may bedesirable to treat the surface of the metal base portion of the glassloading equipment prior to application of the metal support layerthereon so as to enhance the bonding of the support layer to the basemetal. Conventional techniques may be employed in this regard.

As previously indicated, after the support metal layer has been appliedand formed onto the base metal of the glass loading equipment there isthen applied to the support metal layer, in a manner per se previouslydone, a solid film glass lubricant layer. That layer is composed of abinder and effective lubricating amounts of a lubricating pigment.Exemplary of these pigments are graphite and molybdenum disulfide withgraphite being especially highly preferred. Polymeric materials areemployed to function as the binder for the graphite, or otherlubricating pigments. Particularly preferred binders are the curable,thermosettable polymers. Thus, for example, graphite, is applied inadmixture with a polymer, preferably a curable, thermosettable polymer,in a suitable liquid vehicle onto the surface of the supporting, flamesprayed or plasma sprayed, metal layer. The vehicle is evaporated andthe pigment and polymer formed into a homogeneous film by curing thecurable, thermosettable polymer which effects the binding of thelubricating pigment therein. The curing may be done by heating at atemperature and for a time sufficient to cure to a hard thermoset stateor the polymer may be cured with an appropriate catalyst withoutheating. The application of the lubricating pigment along with thepolymer can be done by conventional techniques such as brushing,spraying, or flow coating. The lubricant pigment will be used in aneffective lubricating amount. Suitable results will be obtained byemploying a weight ratio of lubricating pigment to polymer on the orderof about 0.8:1 to about 2:1 and, for example, if graphite is employedquite desirable results will be obtained using a weight ratio betweenabout 1:1 to about 1.75:1. The polymers which are employed as a binderfor the lubricating pigments are conventional and well known in the art.Exemplary of suitable thermosettable polymers are silicones,phenoplasts, melamine formaldehydes (including alkylated melamineformaldehydes), epoxides and inorganic phosphates. Particularlypreferred materials are the phenoplasts and the organopolysiloxanes.Preferably when the phenoplasts or organopolysiloxanes are employed thesolid film lubricant layer will be formed by applying, preferably byspraying a dispersion of the lubricating pigment, for example, graphite,in an organic solvent solution of a further-curable, thermosettablephenoplast or organopolysiloxane. Additionally, the dispersion caninclude, as is well known, suitable adjuvants such as, for example,thixotropes and the like which are employed to adjust the dispersion toa desired flow depending on the nature of the application technique andit can likewise include effective cure promoting amounts of conventionalcure promoters for the polymers employed. Exemplary of suitable curepromoters are the melamine formaldehyde partial condensate resinsincluding, for example, the alkylated, i.e., lower alkylated, forexample, C₁ -C₅ alkylated melamine formaldehyde partial condensateresins, such as for example, butylated melamine formaldehyde partialcondensate resins. Typically the cure promoters will be used in anamount of less than about 15% by weight based on the polymer solids. Thephenoplasts which are employed are well known in the art and are thepartial condensate products of phenol and aldehydes and especiallyphenol and formaldehyde. These further-curable, thermosettablephenolaldehyde resins are widely available from numerous suppliers.Similarly the further-curable, thermosettable organopolysiloxanes whichare employed are likewise well known in the art, and are widelyavailable commercially. Typically these materials will be hydrolysis andcondensation products of monoalkyltrifunctionalsilanes and/ormonophenyltrifunctionalsilanes, or condensation and hydrolysis productsof mixtures of monoalkyltrifunctionalsilanes, and/ormonophenyltrifunctionalsilanes, with dialkyldifunctionalsilanes, and/ordiphenyldifunctionalsilanes. The alkyl referred to above will generallybe a lower alkyl for example, a C₁ -C₃ alkyl with methyl beingparticularly preferred. Reference in the above with regard todifunctional and trifunctional silanes means that the silanes in thecase of difunctionality will have two hydrolyzable groups thereon and,similarly, a trifunctional silane will have three hydrolyzable groupsthereon. As is well known these hydrolyzable groups are typically thehalide groups, for example, chloride groups, as well as the alkoxygroups, for example, the alkoxy groups wherein the alkyl portion hasfrom one up to about 5 carbon atoms, with ethoxy being especiallypreferred. One especially suitable further-curable, thermosettableorganopolysiloxane is a methylphenylsiloxane having an R:Si ratio on theorder of about 1.4, the R:Si ratio, as is known in the art, being theratio of the organic moieties directly bonded to silicon atoms, andhighly desirable results will be obtained using a mole ratio of methylto phenyl radicals on the order of about 3:1 to 4:1. In making up anorganic solvent solution of the thermosettable, further-curable polymera wide variety of solvents may be employed including alkanes, aromaticsolvents, ethers, alcohols, esters, and the like; for example, xylenetypically produces quite satisfactory results. The concentration of thefurther-curable, thermosettable polymers in the organic solvent solutionmay vary over a wide range with suitable results being obtained using aconcentration of between about 10 to about 60% by weight ofcurable-thermosettable polymer solids (based on solvent and polymersolids only) and quite desirable results being obtained by utilizingabout 25 to about 55% by weight of the thermosettable, further-curablepolymer. The curing of the further-curable, thermosettable polymers totheir cured, thermoset hard, condition will be done under conditions oftime and temperature which are conventional in the art for effectingthese purposes.

While the above describes the present invention with sufficientparticularity to enable those skilled in the art to make and use same,and generally sets forth some of the best modes contemplated, therenonetheless follows a representative example which will even yet moreclearly allow those skilled in the art to make and use the presentinvention,

The glass loading equipment which was employed was a conventional chuteor trough which is U-shaped in cross section and the base metal of whichwas iron, although other metals, e.g. aluminum would be equallysatisfactory. The chute was first passed through a conventional glassannealing lehr whereby it was heated to effect a baking off of residualorganics on the surface. The glass contacting surface of this chute wasthen conventionally grit blasted and a primer, or bond, coat of an alloyof nickel and chromium in an amount of about 0.5 parts chromium and 92.6parts by weight nickel was flame sprayed from an oxyacetylene spray ontothe grit blasted surface. Sufficient material was applied until it justbarely became visible. Subsequently there was applied, onto the primedsubstrate, the transition metal support layer for the solid filmlubricant. This support metal was an alloy of 61 parts nickel and about7 parts chromium and included tungsten carbide which functions toincrease the hardness of the support layer. The amount of tungstencarbide was generally on the order of about 12 parts by weight. Thenickel-chromium alloy which was applied initially as the prime coat isavailable from Eutectic Castolin Institute under their designationXuperbond and the nickel-chromium alloy containing the tungsten carbide,used as the support layer, was obtained from Eutectic Castolin Instituteas their designation Diamax 19112. Immediately prior to the flamespraying of the support layer onto the chutes, the latter had beenheated in the temperature range of about 200° to about 500° F., andhence were generally in this temperature range during flame spraying.The flame spraying of the material to form the support layer was done toproduce a textured or rough coating having a depth of about 0.012 inchemploying a Roto-Tec flame spray gun also available from the above notedsupplier. The solid film lubricant was prepared by admixing afurther-curable, thermosettable organopolysiloxane (R:Si ratio of about1.40:1, methyl:phenyl ratio of about 3.60:1 manufactured from a mixtureof phenyltriethoxysilane, methyltriethoxysilane, anddimethyldiethoxysilane) along with an organic solvent, which in thisinstance was xylene with the amount of organopolysiloxane being such asto form a solution of about 50% by weight organopolysiloxane. There wasthen combined into that solution particulate graphite (obtained fromAsbury Graphite Mills, Inc. under their designation A-98) with theamount of graphite employed being in a weight ratio to theorganopolysiloxane solids of about 1.5:1. Additionally, there wasemployed as a cure promoter (about 5% by weight of the siloxane) abutylated melamine formaldehyde supplied commercially by KoppersChemical Company under their designation Koprez 70-10. The material wassprayed onto the support coating to form a solid film glass lubricantlayer which overcovers the support layer and had a thickness of about0.014 inches. Curing of the organopolysiloxane was effected by heatingat a temperature of about 600° F. for about 1 hour. The glass deliverychute so formed having the solid film glass lubricant layer supported bythe intermediate transition metal layer was then employed in a glassmanufacturing facility to gravitationally convey glass gobs from theshears to a blank mold. Typical life times which were obtained weregreater than 2 months and it will be readily appreciated, by thoseskilled in the art, that this is indeed quite significant.

While the foregoing describes the invention it will, of course, beapparent that modifications are possible which according to the patentlaws and statutes do not depart from the spirit and scope of the presentinvention.

We claim:
 1. In a process for forming glass articles comprisingconveying a charge for formable glass over loading equipment to aforming mold and wherein at least a portion of said loading equipmentcarries, at a formable glass contacting location thereon, a solid filmglass lubricant layer comprising a lubricant pigment dispersed in apolymeric binder, the improvement comprising increasing the effectivelubricating life of said layer by supporting said layer on said loadingequipment with a textured support coating of a transition metal appliedto said loading equipment in a high energy spray said layer being indirect contact with said textured support coating.
 2. The improvement ofclaim 1 wherein said support coating is formed on said loading equipmentby flame spraying.
 3. The improvement of claim 2 wherein said metal isnickel.
 4. The improvement of claim 3 wherein tungsten carbide issprayed along with said transition metal.
 5. The improvement of claim 1wherein said metal is formed on said loading equipment by plasmaspraying.
 6. In a glass gob delivery chute comprising a first metalsurface carrying a solid film glass lubricant layer comprising graphitedispersed in a cured, thermoset polymer the improvement comprising atransition metal support layer for said solid film lubricant disposedintermediate said first metal surface and said glass lubricant layer,said supporting metal layer having a rough surface and being appliedfrom a high energy spray, said glass lubricant layer being in directcontact with said supporting metal layer.
 7. The improvement of claim 6wherein said transition metal layer comprises at least about 50% byweight of a transition metal and 0 to about 18% by weight of at leastone transition metal carbide or transition metal nitride.
 8. Theimprovement of claim 7 wherein said carbide is tungsten carbide.
 9. In amethod for forming glass loading equipment comprising applying unto ametal member a dispersion of graphite in a curable thermosettablepolymer and then curing said polymer to a thermoset condition so as tobind said graphite therein and form a solid film glass lubricant layeron said metal member, the improvement comprising increasing theeffective lubricant life of said layer by applying unto said metalmember in a high energy spray, prior to said application of saidgraphite dispersion, a metal comprising a major amount of a transitionmetal and then applying said graphite dispersion directly onto saidlayer.
 10. The improvement of claim 9 wherein said high energy spray isa flame spray.
 11. The improvement of claim 9 wherein said high energyspray is a plasma spray.
 12. In a method of forming glass comprisingconveying formable glass over loading equipment to a glass forming moldand then forming said glass in said forming mold, the improvementwherein said loading equipment is produced in accordance with the methodof claim 9.